A pretty small query really - dnslint and repadmin - what really differentiates these tools in terms of troubleshooting replication? When and why would you use either one.
REPADMIN is specifically for diagnosing Active Directory replication problems between domain controllers.
DNSLINT is more specifically for testing DNS name resolution issues, although the results of this test can also be useful in troubleshooting replication.
I use both tools to proactively test my domain controllers on a routine basis, and also like to run them after promoting a new DC in order to verify that it is configured properly for DNS resolution and AD replication.
Have you taken the time to read any of the TechNet articles about both of these tools?